Gear pump



March 24,1970 F. KACZQRQWSKI 3,502,033

GEAR PUMP Filed Dec. 23, 1968 2 Sheets-Sheet 1 ymxwk INVENTOR. FELIX KACZOROWSKI m g g; iww

ATT'YS March 24, 1970 IF. KACZOROWSKI 3,502,033

GEAR PUMP Filed Dec. 23. 1968 3 Sheets-Sheet 2 I N VEN TOR:

FELIX KACZOROWSKI AT T" YS United States Patent O 3,502,033 GEAR PUMP Felix Kaczrowski, Remscheid-Lennep, Germany, assiguor to Barmag Barmer Maschinenfabrik Aktiengesellschaft, Wuppertal, Germany Filed Dec. 23, 1968, Ser. No. 786,263 Claims priority, application Germany, Dec. 23, 1967,

Int. Cl. F04c 1/04, 23/00 US. Cl. 103126 7 Claims ABSTRACT OF THE DISCLOSURE Gear pump having juxtaposed plates forming pump casing, at least two pairs of gears, the driven gear of one pair being journaled on a tubular shaft, and other set of gear pairs having a short, fluid-discharge passage including the tubular shaft.

BACKGROUND OF THE INVENTION It is a known feature to employ gear pumps with one or several sets of gears set up in separate casings for the conveying of viscous fluids. Each gear pair set consists of one or more driving gears fastened on the driving shaft and of driven gears meshing with the drive gears. German Patent No. 815,000 shows in FIGURE 7 a gear pump, in the casing of which the fluid outlet passage runs radially from the gear along one front side of this gear to the bore of a tubular gear journal. In this arrangement, the gear is acted upon axially by the high pressure of the fluid. Because of this, considerable wear occurs at the opposite front surface of the gear. In the US. Patent 2,818,023, a gear pump is shown, in the casing of which the fluid outlet passage of the pump in FIG. leads through the back wall up to the cover plate. Here it turns parallel to this cover plate in the form of a channel formed in the back wall and directed away from the outlet side. It ultimately leads to a tubular journal. In this arrangement, the medium conveyed by the right set of pumps covers a very long distance in the pump casing. This results in decomposition of heat-sensitive plastic material, and, in any case, in denier differences in the filaments emerging from the nozzels. In the British Patent No. 731,101, a gear pump consisting of two sets of pumps is described. The two driven gear wheels are respectively set up on a shaft. Both shafts are set up in a bore of the pump casing. The fluid entrance takes place from the surface opposite to the driving side through a blind-end bore which is placed into the hollow shaft facing this surface. A radial bore in this shaft connects the blind-end bore with the further passage in the middle portion of the pump casing. The manufacture and assembly of this shaft is very expensive.

BRIEF DESCRIPTION OF THE INVENTION The primary objects of this invention concern gear pumps having a casing with discharge passages wherein the routes of the pumped liquid are short for all sets of gears and wherein the parts can be easily produced and assembled.

This discharge lines of at least one set of gears in the pump casing are. set up in such a manner that they are oriented relative to the respective discharges into an intermediate plate of the casing in the direction of the outlet opening and from this intermediate plate, in passages completely separated from the gears, rectilinearly to the casing bores which receive the hollow journal shafts.

It has proved to be very advantageous to keep the discharge lines completely separated from the gears in the intermediate: plate by providing such lines in a face of the 3,502,033 Patented Mar. 24. 1970 intermediate plate facing away from the gears. But such lines can also be set up as bore within the intermediate plate at an acute angle to its faces.

Also, the hollow shafts of the driven gears are mounted in bores in the casing and are stub shafts extending an axial distance in the. bores which are at least equal to the diameter or the width of the respective discharge lines immediately preceding such bores. In this manner, without expensive machining, a very short connection is provided between the outlet or discharge side of each pair and the respective discharge opening in the casing.

Since the pressure does not have any effect upon the faces of the gears, the service life of the pump is considerably lengthened. Operating interruptions because of accumulated decomposition products of the conveyed media deposited in the passages occur after a longer period of time.

DESCRIPTION OF DRAWINGS The improvements of the subject invention and the advantages attendant therewith will be more fully appreciated from the following description of preferred embodiments thereof, which are illustrated in the drawings, wherein:

FIG. 1 and FIG. 2 are section views of a first embodiment, taken respectively on section planes 11 of FIG. 2 and 22 of FIG. 1;

FIG. 3 and FIG. 4 are section views of a second embodiment, taken respectively on section planes 33 of FIG. 4 and 4-4 of FIG-3; and

FIG. 5 and FIG. 6 are section views of a third embodiment of the invention, taken respectively on section planes 55 of FIG. 6 and 66 of FIG. 5.

Referring to the drawings, the embodiment of FIGS. 1 and 2 is a gear pump 10 having a front, discharge plate 11 and a rear, feed plate 12. A plurality of intermediate plates 13, 14, 15 and 16 are sandwiched between plates 11 and 12. The six plates 1116 are tightly pressed together in face-to-face relationship by four bolts 17 extending transversely therethrough.

The intermediate plate 13 has a pair of intersecting, substantially circular openings 18 and 19 which respectively receive a gear pair set later described. The intermediate plate 16 has a similar pair of intersecting, circular holes 20 and 21 which receive a second gear pair set, also later described.

The plates 11-16 are provided with axially aligned holes providing an axial passage 22, which receives and rotatably journals therein the drive shaft 23. These plates also have a second series of axially aligned holes which together form an axial passage 24, parallel to the passage 22. The portion of the passage 24 in the plates 12, 13 and 14 receive a stub shaft 25, which may be tightly seated therein or may be rotatably journaled therein. The portion of the passage .24 in the plates 11, 15 and 16 receives a tubular or hollow shaft 26, which preferably is tightly seated therein.

The drive shaft 23 rotatably drives the gears 27 and 29, which are splined thereon by the adjusting springs 28 and 30, respectively. The gear teeth 31 of the gears 27 and 29 mesh with the gear teeth 32 of the driven gears 33 and 34, which are rotatably journaled on or by the stub shaft 25 and 26. Thus, the gear pump of FIGS. 1 and 2 comprises a casing containing two gear pair sets. The gear pair sets have their discharge passages below the central, intermeshing section thereof.

The fluid enters the pump through an inlet passage 35 which extends through the rear plate 12, intersects laterally the holes 18 and 19, extends through the intermediate plates 14 and 15 and intersects the holes 20 and 21 laterally. Thus, the passage 35 is an inlet manifold passage for both gear pair sets. It is impelled from this passage by the teeth of the respective gears around the outer peripheries of the holes 18-21 to the discharge passages.

The fluid on the discharge side of the gear pair set 29 and 34 is discharged into the outlet passage 38. The shallow depressions 36 and 37 extending from the discharge outlet 38 function as pressure relief clearances for fluid entrapped between meshing gear teeth. The fluid on the discharge side of the gear pair set 27 and 33 is discharged into the passage 41 and flows into a radial passage 42 formed by machining a recess or groove in the face 46 of the intermediate plate 14. The shallow d:- pressions 32 and 40 extending from the discharge outlet 41 again function as pressure relief clearances for fluid entrapped between meshing gear teeth. The recess or groove machined into the intermediate plate 14, together with the opposing face 47 of intermediate plate 15 forms the endosed passage 42. The passage 42 intersects at the opening 43 the free space 44 located between the stub shaft 25 and the hollow stub shaft 26. The free space 44 in turn communicates with the discharge passage 45 formed by the tubular stub shaft 26.

It will be noted that the shallow depressions 36, 37, 39, 40, the passages 38, 40, 41, 42, space 44 and passage 45 can be made by simple machining operations in the appropriate plates forming the casing 10.

The embodiment of FIGS. 3 and 4 is similar in most respects to the embodiment of FIGS. 1 and 2. Where applicable, like numerals designate like parts. The gear pump 10a illustrated in FIGS. 3 and 4 differs primarily in the orientation of the passage connecting the fluid outlet passage 40 with the space 44. In lieu of forming a passage 42 by a recess or groove in the face 46 as illustrated in FIGS. 1 and 2, the connecting passage 48 is a diagonal bore which intersects the space 44 at the opening 49 and intersects the passage 40 at the opposite end thereof.

The embodiment illustrated in FIGS. and 6 is similar in most respects to the embodiment of FIGS. 1 and 2. The pump b has within its casing four gear pair sets instead of two, all of which are driven from the common drive shaft 23a. Where applicable, like numerals designate like parts and in the remainder of instances the numerals followed by the letters a and b find their counterpart in the parts designated by numerals only in FIGS. 1 and 2.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A gear pump comprising a pump housing formed by juxtaposed plates in face-to-face relationship, means in two, separate intermediate plates forming at least two pumping chambers, a pair of intermeshed gears in each chamber, a drive shaft extending transversely through said plates and connected to one gear of each pair of gears for rotatably driving said gears, a tubular stud shaft extending transversely from an outer face of said casing through one chamber, the driven gear in said one chamber being rotatably journalled on said tubular shaft, liquid discharge passage means communicating with the other chamber and extending transversely across the intermediate plate containing said other chamber, a solid stub shaft axially aligned with said tubular stub shaft and exdriven gear in said other chamber being rotatably mounted on said solid stub shaft, the opposed ends of said shafts having a space therebetween, and additional passage means in an intermediate plate between said pumping chambers and connecting said liquid discharge passage means and said space to provide a path of flow of pumped liquid from said other chamber via said additional passage means and said space to said tubular shaft.

2. A gear pump as claimed in claim 1 wherein said additional passage means includes a groove or bore in the intermediate plate next adjacent to said intermediate plate containing said other chamber.

3. A gear pump as claimed in claim 2 wherein said additional passage means includes a groove in the face of said next adjacent plate, said face being the face remote from said intermediate plate containing said other chamber.

4. A gear pump as claimed in claim 2 wherein said additional passage means includes a bore in said next adjacent plate, said bore extending angularly from said liquid discharge passage means to a chamber communicating with said tubular shaft.

5. A gear pump as claimed in claims 1, 2, 3 or 4 wherein the axial length of said tubular shaft is at least equal to the diameter or Width of said additional passage means.

6. A gear pump comprising a pump housing formed by juxtaposed plates in face-to-face relationship, means in two, separate intermediate plates forming at least two pumping chambers, a pair of additional intermediate plates between said separate intermediate plates, a pair of intermeshed gears in each chamber, a drive shaft extending transversely through said plates and connected to one gear of each pair of gears for rotatably driving said gears, a tubular shaft extending transversely from an outer face of said casing through one chamber, the driven gear in said one chamber being rotatably journalled thereon, a liquid discharge passage communicating with the other chamber and extending transversely across the intermediate plate containing said other chamber, a groove in only one of the contacting faces of said additional intermediate plates, said groove extending from said liquid discharge passage to said tubular shaft and thereby providing a passage for pumped liquid from said other chamber into said tubular shaft.

7. A gear pump as claimed in claim 6, a solid stub shaft axially aligned with said tubular stub shaft and extending transversely through said other chamber, the driven gear in said other chamber being rotatably mounted on said solid stub shaft, the opposed ends of said shafts having a space therebetween, and said groove communicating with said space to provide a passage for flow of pumped liquid from said other chamber via said groove and said space into said tubular shaft.

References Cited UNITED STATES PATENTS 2,207,493 7/ 1940 Dartelen. 2,533,320 12/1950 Hull et al. 2,685,839 8/ 1954 Vandenburgh. 2,818,023 12/1957 Lundstrom. 3,314,369 4/1967 Yonei t a1.

DONLEY J. STOCKING, Primary Examiner W. J. GOODLIN, Assistant Examiner US. C X-R, 230158 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3; 5 33 PO-IOSU Dated March 2 1370 Inventor(s) Felix Kaczorowski It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, 11ne 3, "Kaczrowski" should read Kaczorowski line 65, 'respective discharges" should read respective gear discharges Coiumn 2, line 10, "each pair" should read each gear p8. I -'o Column 3, line 64, Claim 1, "stud" should read stub SIGN D AND SEALED 

